The present invention relates generally to an apparatus and method for percutaneous access to the inside of the body. In particular, the invention relates to a transparent sheath with a radiopaque marking at the distal end and a fastener for securing a guidewire or catheter near the proximal end of the sheath.
Medical procedures utilizing interventional instruments (e.g., endoscopes) inserted through the skin often require preservation of the access path after the instrument is withdrawn from the body. Typically, these procedures require insertion of a sheath into the body along a guidewire previously coupled to the interventional instrument. The sheath prevents the tract established by the interventional device from closing or collapsing. One example procedure involves insertion of a dilation catheter and a guidewire along the nephrostomy tract. Once properly positioned in the body, a balloon near the distal end of the catheter is inflated to dilate the tract. A sheath is then advanced through the nephrostomy tract before the tract substantially collapses.
This procedure has inherent problems. The sheath is typically radiopaque, thus the physician cannot observe objects within or obstructed by the sheath by standard fluoroscopic techniques. In addition, optical imaging devices inserted through the sheath are unable to look out radially, thus prohibiting accurate location of objects adjacent to the sheath. Moreover, the guidewire may migrate during the exchange of instruments through the sheath, thus inhibiting placement of additional instruments along the tract.
A transparent sheath for access to the inside of a human or animal body has been developed which is useful in a variety of medical applications including, but not limited to, the exchange of instruments, drainage of fluids and removal of objects (e.g., kidney stones). The sheath can be used to provide percutaneous access to the inside of the body or it can be used in natural body orifices. Applications include urological procedures, stent delivery and laparoscopic procedures. In one embodiment, the sheath includes an elongated hollow member with a radiopaque marking at the distal end. In another embodiment, the sheath includes an elongated hollow member with at least one radiopaque marking along the length of the sheath and one or more fasteners near the proximal end of the sheath for securing other medical devices thereon such as guidewires and catheters. The sheath can be optically or fluoroscopically transparent or transparent to ultrasound. Preferably, the sheath is transparent to all three visible light (including IR and UV lights), ultrasound, and x-rays. The radiopaque marking may be disposed on the outer or inner circumference of the sheath. The radiopaque marking may be disposed on an end face of the distal end or may occupy the whole length of the sheath such as a line or spiral. One or more additional radiopaque markings may be used for identification such as in a broken line, a series or rings, or alphanumerical characters disposed along the length of the sheath (e.g., product numbers and logos). An additional radiopaque line or spiral running the length of the sheath from the distal end to the proximal end may be used to enhance visibility during the procedure.
The distal end face may be approximately perpendicular to the longitudinal axis of the sheath. In an alternative embodiment, the distal end face and longitudinal axis may define an angle less than 90xc2x0 to minimize trauma to the issue during insertion and facilitate placement of the sheath.
The transparent sheath may include one or more fasteners at its proximal end for securing other medical devices thereon such as a guidewire or catheter and maintaining the sheath at a desired position within the body. The fastener may be any device or adaptation at the proximal end of the sheath which prevents other medical devices from migrating during the procedure. Example fasteners include clips, slots, or straps such as Velcro(trademark) straps or elastic bands or a combination thereof. In one embodiment, the fastener is a retaining slot which provides an interference fit to hold the other medical device. The retaining slot may also include an opening at the end of the slot which is opposite the proximal end face of the sheath wherein the opening accepts the other medical device and restricts its longitudinal movements back and forth or migration back out of the slot through an interference fit. In yet another embodiment, a magnet is disposed adjacent to the retaining slot to secure a ferromagnetic medical device such as a guidewire.
The invention also features a method for access to the inside of a body. The method includes the steps of inserting a first medical device through a body lumen, then inserting over the second medical device such as the transparent sheath of the invention. Once the sheath is disposed at a desired location in the body, the first medical device is secured to the second medical device in the fastener. In one embodiment, the first medical device is secured by an interference fit in an opening adjacent to an end of a slot disposed at the proximal end of the second medical device, the end of the slot being opposite the proximal end face. In another embodiment, the first medical device is secured within the slot by a magnet fixed adjacent to the slot.
The method may be used for naturally existing body lumens or body lumens created by the practitioner with the use of an interventional device such as a needle or a trochar. Thus, in one embodiment, the method of the invention permits access to the inside of a body percutaneously. The percutaneous method further includes the step of inserting an interventional device into the body. The interventional device may be coupled to a guidewire or catheter. Once, the lumen is created the interventional device is decoupled from the guidewire or catheter. A transparent sheath of the invention with a fastener near its proximal end and radiopaque markings along its length is inserted into the body over the guidewire or catheter. The interventional device is then removed from the body. In one embodiment, the sheath may be inserted into the body over the guidewire after removal of the interventional device. In another embodiment, the sheath may be inserted over the interventional device before its removal.
In yet another embodiment, the methods of the invention further include the step of viewing through the first medical device objects in the body relative to a radiopaque marking at the distal end. The invention also features a method of viewing objects within or near the first medical device in a body. Objects inside or near the first medical device are viewed relative to the radiopaque marking at the distal end with an imaging device or disposed along the length of the elongated hollow body. The imaging device may be located within the first medical device or be outside of the body. In one embodiment, the imaging device is a side-viewing endoscope placed within the first medical device. In another embodiment, the imaging device is a fluoroscopic imaging system viewing from outside the body.